[Asterisk-Users] Call Center sofphone

[Mimmus]

Hi,
we are trying to setup a prototype Asterisk machine for our call center
(15-20 users).
We are encountering some difficulties in finding a 'good' softphone
(SIP/IAX).
Suggestion/experience?
Is there some product available for Windows with modifiable code?
Is there some freelance developer potentially interested in creating custom
version for us?

Thanks in advance
-- 
Mimmus